perf: Handle compat ioctl
[linux-3.10.git] / kernel / jump_label.c
1 /*
2  * jump label support
3  *
4  * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
5  * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
6  *
7  */
8 #include <linux/memory.h>
9 #include <linux/uaccess.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/sort.h>
14 #include <linux/err.h>
15 #include <linux/static_key.h>
16
17 #ifdef HAVE_JUMP_LABEL
18
19 /* mutex to protect coming/going of the the jump_label table */
20 static DEFINE_MUTEX(jump_label_mutex);
21
22 void jump_label_lock(void)
23 {
24         mutex_lock(&jump_label_mutex);
25 }
26
27 void jump_label_unlock(void)
28 {
29         mutex_unlock(&jump_label_mutex);
30 }
31
32 static int jump_label_cmp(const void *a, const void *b)
33 {
34         const struct jump_entry *jea = a;
35         const struct jump_entry *jeb = b;
36
37         if (jea->key < jeb->key)
38                 return -1;
39
40         if (jea->key > jeb->key)
41                 return 1;
42
43         return 0;
44 }
45
46 static void
47 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
48 {
49         unsigned long size;
50
51         size = (((unsigned long)stop - (unsigned long)start)
52                                         / sizeof(struct jump_entry));
53         sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
54 }
55
56 static void jump_label_update(struct static_key *key, int enable);
57
58 void static_key_slow_inc(struct static_key *key)
59 {
60         if (atomic_inc_not_zero(&key->enabled))
61                 return;
62
63         jump_label_lock();
64         if (atomic_read(&key->enabled) == 0) {
65                 if (!jump_label_get_branch_default(key))
66                         jump_label_update(key, JUMP_LABEL_ENABLE);
67                 else
68                         jump_label_update(key, JUMP_LABEL_DISABLE);
69         }
70         atomic_inc(&key->enabled);
71         jump_label_unlock();
72 }
73 EXPORT_SYMBOL_GPL(static_key_slow_inc);
74
75 static void __static_key_slow_dec(struct static_key *key,
76                 unsigned long rate_limit, struct delayed_work *work)
77 {
78         if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
79                 WARN(atomic_read(&key->enabled) < 0,
80                      "jump label: negative count!\n");
81                 return;
82         }
83
84         if (rate_limit) {
85                 atomic_inc(&key->enabled);
86                 schedule_delayed_work(work, rate_limit);
87         } else {
88                 if (!jump_label_get_branch_default(key))
89                         jump_label_update(key, JUMP_LABEL_DISABLE);
90                 else
91                         jump_label_update(key, JUMP_LABEL_ENABLE);
92         }
93         jump_label_unlock();
94 }
95
96 static void jump_label_update_timeout(struct work_struct *work)
97 {
98         struct static_key_deferred *key =
99                 container_of(work, struct static_key_deferred, work.work);
100         __static_key_slow_dec(&key->key, 0, NULL);
101 }
102
103 void static_key_slow_dec(struct static_key *key)
104 {
105         __static_key_slow_dec(key, 0, NULL);
106 }
107 EXPORT_SYMBOL_GPL(static_key_slow_dec);
108
109 void static_key_slow_dec_deferred(struct static_key_deferred *key)
110 {
111         __static_key_slow_dec(&key->key, key->timeout, &key->work);
112 }
113 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
114
115 void jump_label_rate_limit(struct static_key_deferred *key,
116                 unsigned long rl)
117 {
118         key->timeout = rl;
119         INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
120 }
121 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
122
123 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
124 {
125         if (entry->code <= (unsigned long)end &&
126                 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
127                 return 1;
128
129         return 0;
130 }
131
132 static int __jump_label_text_reserved(struct jump_entry *iter_start,
133                 struct jump_entry *iter_stop, void *start, void *end)
134 {
135         struct jump_entry *iter;
136
137         iter = iter_start;
138         while (iter < iter_stop) {
139                 if (addr_conflict(iter, start, end))
140                         return 1;
141                 iter++;
142         }
143
144         return 0;
145 }
146
147 /* 
148  * Update code which is definitely not currently executing.
149  * Architectures which need heavyweight synchronization to modify
150  * running code can override this to make the non-live update case
151  * cheaper.
152  */
153 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
154                                             enum jump_label_type type)
155 {
156         arch_jump_label_transform(entry, type); 
157 }
158
159 static void __jump_label_update(struct static_key *key,
160                                 struct jump_entry *entry,
161                                 struct jump_entry *stop, int enable)
162 {
163         for (; (entry < stop) &&
164               (entry->key == (jump_label_t)(unsigned long)key);
165               entry++) {
166                 /*
167                  * entry->code set to 0 invalidates module init text sections
168                  * kernel_text_address() verifies we are not in core kernel
169                  * init code, see jump_label_invalidate_module_init().
170                  */
171                 if (entry->code && kernel_text_address(entry->code))
172                         arch_jump_label_transform(entry, enable);
173         }
174 }
175
176 static enum jump_label_type jump_label_type(struct static_key *key)
177 {
178         bool true_branch = jump_label_get_branch_default(key);
179         bool state = static_key_enabled(key);
180
181         if ((!true_branch && state) || (true_branch && !state))
182                 return JUMP_LABEL_ENABLE;
183
184         return JUMP_LABEL_DISABLE;
185 }
186
187 void __init jump_label_init(void)
188 {
189         struct jump_entry *iter_start = __start___jump_table;
190         struct jump_entry *iter_stop = __stop___jump_table;
191         struct static_key *key = NULL;
192         struct jump_entry *iter;
193
194         jump_label_lock();
195         jump_label_sort_entries(iter_start, iter_stop);
196
197         for (iter = iter_start; iter < iter_stop; iter++) {
198                 struct static_key *iterk;
199
200                 iterk = (struct static_key *)(unsigned long)iter->key;
201                 arch_jump_label_transform_static(iter, jump_label_type(iterk));
202                 if (iterk == key)
203                         continue;
204
205                 key = iterk;
206                 /*
207                  * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
208                  */
209                 *((unsigned long *)&key->entries) += (unsigned long)iter;
210 #ifdef CONFIG_MODULES
211                 key->next = NULL;
212 #endif
213         }
214         jump_label_unlock();
215 }
216
217 #ifdef CONFIG_MODULES
218
219 struct static_key_mod {
220         struct static_key_mod *next;
221         struct jump_entry *entries;
222         struct module *mod;
223 };
224
225 static int __jump_label_mod_text_reserved(void *start, void *end)
226 {
227         struct module *mod;
228
229         mod = __module_text_address((unsigned long)start);
230         if (!mod)
231                 return 0;
232
233         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
234
235         return __jump_label_text_reserved(mod->jump_entries,
236                                 mod->jump_entries + mod->num_jump_entries,
237                                 start, end);
238 }
239
240 static void __jump_label_mod_update(struct static_key *key, int enable)
241 {
242         struct static_key_mod *mod = key->next;
243
244         while (mod) {
245                 struct module *m = mod->mod;
246
247                 __jump_label_update(key, mod->entries,
248                                     m->jump_entries + m->num_jump_entries,
249                                     enable);
250                 mod = mod->next;
251         }
252 }
253
254 /***
255  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
256  * @mod: module to patch
257  *
258  * Allow for run-time selection of the optimal nops. Before the module
259  * loads patch these with arch_get_jump_label_nop(), which is specified by
260  * the arch specific jump label code.
261  */
262 void jump_label_apply_nops(struct module *mod)
263 {
264         struct jump_entry *iter_start = mod->jump_entries;
265         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
266         struct jump_entry *iter;
267
268         /* if the module doesn't have jump label entries, just return */
269         if (iter_start == iter_stop)
270                 return;
271
272         for (iter = iter_start; iter < iter_stop; iter++) {
273                 arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
274         }
275 }
276
277 static int jump_label_add_module(struct module *mod)
278 {
279         struct jump_entry *iter_start = mod->jump_entries;
280         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
281         struct jump_entry *iter;
282         struct static_key *key = NULL;
283         struct static_key_mod *jlm;
284
285         /* if the module doesn't have jump label entries, just return */
286         if (iter_start == iter_stop)
287                 return 0;
288
289         jump_label_sort_entries(iter_start, iter_stop);
290
291         for (iter = iter_start; iter < iter_stop; iter++) {
292                 struct static_key *iterk;
293
294                 iterk = (struct static_key *)(unsigned long)iter->key;
295                 if (iterk == key)
296                         continue;
297
298                 key = iterk;
299                 if (__module_address(iter->key) == mod) {
300                         /*
301                          * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
302                          */
303                         *((unsigned long *)&key->entries) += (unsigned long)iter;
304                         key->next = NULL;
305                         continue;
306                 }
307                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
308                 if (!jlm)
309                         return -ENOMEM;
310                 jlm->mod = mod;
311                 jlm->entries = iter;
312                 jlm->next = key->next;
313                 key->next = jlm;
314
315                 if (jump_label_type(key) == JUMP_LABEL_ENABLE)
316                         __jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE);
317         }
318
319         return 0;
320 }
321
322 static void jump_label_del_module(struct module *mod)
323 {
324         struct jump_entry *iter_start = mod->jump_entries;
325         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
326         struct jump_entry *iter;
327         struct static_key *key = NULL;
328         struct static_key_mod *jlm, **prev;
329
330         for (iter = iter_start; iter < iter_stop; iter++) {
331                 if (iter->key == (jump_label_t)(unsigned long)key)
332                         continue;
333
334                 key = (struct static_key *)(unsigned long)iter->key;
335
336                 if (__module_address(iter->key) == mod)
337                         continue;
338
339                 prev = &key->next;
340                 jlm = key->next;
341
342                 while (jlm && jlm->mod != mod) {
343                         prev = &jlm->next;
344                         jlm = jlm->next;
345                 }
346
347                 if (jlm) {
348                         *prev = jlm->next;
349                         kfree(jlm);
350                 }
351         }
352 }
353
354 static void jump_label_invalidate_module_init(struct module *mod)
355 {
356         struct jump_entry *iter_start = mod->jump_entries;
357         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
358         struct jump_entry *iter;
359
360         for (iter = iter_start; iter < iter_stop; iter++) {
361                 if (within_module_init(iter->code, mod))
362                         iter->code = 0;
363         }
364 }
365
366 static int
367 jump_label_module_notify(struct notifier_block *self, unsigned long val,
368                          void *data)
369 {
370         struct module *mod = data;
371         int ret = 0;
372
373         switch (val) {
374         case MODULE_STATE_COMING:
375                 jump_label_lock();
376                 ret = jump_label_add_module(mod);
377                 if (ret)
378                         jump_label_del_module(mod);
379                 jump_label_unlock();
380                 break;
381         case MODULE_STATE_GOING:
382                 jump_label_lock();
383                 jump_label_del_module(mod);
384                 jump_label_unlock();
385                 break;
386         case MODULE_STATE_LIVE:
387                 jump_label_lock();
388                 jump_label_invalidate_module_init(mod);
389                 jump_label_unlock();
390                 break;
391         }
392
393         return notifier_from_errno(ret);
394 }
395
396 struct notifier_block jump_label_module_nb = {
397         .notifier_call = jump_label_module_notify,
398         .priority = 1, /* higher than tracepoints */
399 };
400
401 static __init int jump_label_init_module(void)
402 {
403         return register_module_notifier(&jump_label_module_nb);
404 }
405 early_initcall(jump_label_init_module);
406
407 #endif /* CONFIG_MODULES */
408
409 /***
410  * jump_label_text_reserved - check if addr range is reserved
411  * @start: start text addr
412  * @end: end text addr
413  *
414  * checks if the text addr located between @start and @end
415  * overlaps with any of the jump label patch addresses. Code
416  * that wants to modify kernel text should first verify that
417  * it does not overlap with any of the jump label addresses.
418  * Caller must hold jump_label_mutex.
419  *
420  * returns 1 if there is an overlap, 0 otherwise
421  */
422 int jump_label_text_reserved(void *start, void *end)
423 {
424         int ret = __jump_label_text_reserved(__start___jump_table,
425                         __stop___jump_table, start, end);
426
427         if (ret)
428                 return ret;
429
430 #ifdef CONFIG_MODULES
431         ret = __jump_label_mod_text_reserved(start, end);
432 #endif
433         return ret;
434 }
435
436 static void jump_label_update(struct static_key *key, int enable)
437 {
438         struct jump_entry *stop = __stop___jump_table;
439         struct jump_entry *entry = jump_label_get_entries(key);
440
441 #ifdef CONFIG_MODULES
442         struct module *mod = __module_address((unsigned long)key);
443
444         __jump_label_mod_update(key, enable);
445
446         if (mod)
447                 stop = mod->jump_entries + mod->num_jump_entries;
448 #endif
449         /* if there are no users, entry can be NULL */
450         if (entry)
451                 __jump_label_update(key, entry, stop, enable);
452 }
453
454 #endif